Partial purification and characterization of polyphenol oxidase from fresh-cut chinese water chestnut

The characteristics of polyphenol oxidase (PPO) from Chinese water chestnut (CWC) and its potential inhibitors for browning reactions were investigated. PPO was isolated from fresh-cut CWC and was purified on a Sephadex G-100 column, with a yield of total activity close to 10%. The molecular weight, Michaelis constant (K _m), substrate specificity, optimal pH and temperature of CWC PPO were examined. Kinetic studies indicated that the K _m and V _max values of CWC PPO for catechol were 10.32 mmol/L and 6.452 × 10 ⁴ U/min, respectively. The optimal pH and temperature for CWC PPO was 6.5 and 40C, respectively. Among the browning inhibitors tested, 4-hexylresorcinol, at a concentration of 0.3 mmol/L, showed the strongest inhibition (70%) against the PPO activity of CWC, followed by 3.0 mmol/L N-acetyl-L-cysteine with an inhibition of 53%.